Ironmaking and Steelmaking

ABSTRACT

A steelmaking process is disclosed. The process includes producing molten steel and molten steelmaking slag in a steelmaking process, the steelmaking slag including iron units and flux units, and thereafter producing molten iron in a molten bath based direct smelting process using a substantial portion of the steelmaking slag as part of the feed material requirements for the direct smelting process. A direct smelting process is also disclosed. The process includes pre-treating ferrous material including steelmaking slag and thereafter direct smelting molten iron using the pretreated ferrous material as part of the feed material for the process.

FIELD OF THE INVENTION

The present invention relates to steelmaking, particularly steelmakingin an integrated steelmaking plant.

The present invention also relates to ironmaking, particularly via amolten bath based direct smelting process.

The present invention is concerned with improving the economics ofoperating steelmaking plants, particularly integrated steelmakingplants, by making effective use of steelmaking slag and dusts and othersteelmaking plant by-products that are generally regarded as low valuewastes.

The present invention makes it possible to use these steelmakingby-products as feed materials to an ironmaking process and therebyreduce:

(a) the overall amount of waste that is produced by ironmakingoperations and steelmaking operations; and

(b) the amounts of feed materials for ironmaking operations that arerequired from other sources.

The present invention is based on the use of a direct smelting processand apparatus for producing molten iron (which term includes ferrousmetal alloys) that is capable of using steelmaking plant by-products,such as steelmaking slag and dusts, as a feed material for the directsmelting apparatus.

The direct smelting process and apparatus may be part of an integratedsteelmaking plant or may be a separate operation altogether thatprocesses steelmaking by-products produced in one or more than oneseparate steelmaking operation.

BACKGROUND OF THE INVENTION

Traditional iron and steelmaking processes produce slag. Both ironmakingslag and steelmaking slag are considered to be waste products of theserespective processes.

Steelmaking slag typically contains iron units in the form of FeO andflux units in the form of lime (CaO). Typically, the iron units are 35%by weight of the slag and the flux units are 25-35% by weight of theslag.

When the steelmaking slag is disposed of in accordance with prior artpractice, the iron and lime units are lost.

Significant economic and environmental benefits would be gained if itwere possible to recover or reuse iron and lime units from steelmakingslag.

Recycling of steelmaking slag to prior art ironmaking vessels such astraditional blast furnaces in order to recover or reuse the iron andlime units is not considered to be a viable option. One reason for thisis that phosphorus in feed materials that are supplied to typical blastfurnaces tends to partition to the molten iron produced in the furnace.When this molten iron is subsequently supplied to a steelmaking vessel,the phosphorus partitions into the steelmaking slag in order to producesteel of required chemistry. Thus, recycling steelmaking slag to atypical blast furnace is not practical and would simply result in anincreasing phosphorus load in down stream steelmaking vessels. This isundesirable.

Whilst blast furnaces are the traditional option for producing iron fromiron ore, various molten bath-based direct smelting processes have beenproposed with a view to avoiding disadvantages of blast furnaces, suchas the need for sintering and coke making operations. Such directsmelting processes include, by way of example, the Romelt, DIOS (DirectIron Ore Smelting), and HIsmelt processes.

The Romelt process operates at ambient pressure using a molten iron andslag bath with ore fines and non-coking coal dropped in from above.Oxygen and an air/oxygen mixture are injected at each of two elevationsthrough side tuyeres. to stir the melt and post-combust bath gas.

The DIOS process is another molten iron and slag bath-based process andoperates under pressure (1 to 2 bar g) and uses top-feed of coal andore. Unlike Romelt, it uses a top lance for oxygen injection and has afluidised bed system for iron ore pre-reduction. In the smelter, most ofthe reduction occurs in a foamy slag layer. There are significanttemperature and FeOx gradients within the reactor (higher temperaturesand higher FeOx levels at the top of the slag layer).

The HIsmelt process developed by the applicant is another molten ironand slag bath-based process and differs from ‘deep slag’ smelters suchas DIOS and Romelt in that the solids fed to the vessel are injectedsignificantly deeper into the melt. This leads to stronger mixing in thevessel, with hardly any temperature gradients in the liquid. The HIsmeltprocess is described, by way of example, in International applicationsPCT/AU96/00197 (WO 96/31627) and PCT/AU01/00222 (WO 01/64960) in thename of the applicant and the disclosure in these Internationalapplications is incorporated herein by reference.

It has previously been reported that the HIsmelt process is able toprocess iron ores such as high phosphorus Brockman ores and produce apig iron with less than 0.05% phosphorus for downstream steelmaking. Incontrast to the traditional blast furnace, the HIsmelt process has amore oxidising slag which results in extremely effective partitioning ofphosphorus to the slag. During pilot plant testing it was reported bythe applicant that 90 to 95% of the phosphorus fed to the HIsmelt pilotplant vessel reported to the slag. The DIOS and Romelt processes arealso believed to preferentially partition phosphorus to slag.

It has also previously been reported that steelmaking slag in the formof fines can be used as a feed material that is supplied directly to adirect smelting vessel operating in accordance with the HIsmeltprocess—see paper entitled “HIsmelt—Competitive Hot Metal from Ore Finesand Steel Plant Wastes” by the subject inventor, R J Dry, and others,prepared for METEC Congress, 14-15 Jun. 1999. The left hand column onpage 4 of the paper mentions that steel plant reverts, including BOFslag, can provide carbon credits that reduce the coal requirements forthe HIsmelt process flowsheet shown in FIG. 3 of the paper.

SUMMARY OF THE INVENTION

The applicant has carried out further research work into possibleapplications of the HIsmelt process and has realised that there issubstantial scope to use steel plant reverts, particularly steelmakingslag and dusts, as sources of iron units and flux units in directsmelting processes, such as the HIsmelt process.

In particular, in the context of integrated steelmaking, the applicanthas realised that an integrated steelmaking plant that includes directsmelting operations that can efficiently partition phosphorus to theslag and steelmaking operations can be operated so that:

(a) the direct smelting operations take a substantial proportion,typically at least 70% by weight, of the steelmaking slag and dusts thatwould otherwise be regarded as low value wastes and use thesesteelmaking by-products as a valuable part of the feed materials thatcontribute iron and flux units for the direct smelting operations; and

(b) the low phosphorus iron produced in the ironmaking operations can beused as a feed material for the steelmaking operations.

The overall outcome of the above realisation is (a) production of molteniron that can be used in the steelmaking operations, (b) a significantreduction in the net amount of slag and dust produced by the plant, and(c) a significant reduction, typically at least 30% by weight, of theamount of flux that is required from other sources.

In addition, in particular, in the context of ironmaking, the applicanthas realised that a direct smelting apparatus that includes apre-treatment unit that at least preheats and optionally also prereducesferrous feed material and a process based on the use of thepre-treatment unit and a direct smelting vessel is a particularlyeffective option for processing steelmaking slag, with the steelmakingslag being supplied at least in part to the direct smelting vessel viathe pre-treatment unit. This direct smelting apparatus and process maybe part of the above-described integrated steelmaking plant or be aseparate independent operation altogether that processes steelmakingby-products, such as steelmaking slag and dusts, from one or more thanone steelmaking operation.

According to the present invention there is provided, in broad terms, asteelmaking process that includes the steps of:

(a) producing molten steel and molten steelmaking slag in a steelmakingprocess in a steelmaking vessel, the steelmaking slag including ironunits and flux units; and

(b) producing molten iron in a direct smelting process in a directsmelting vessel containing a molten bath of iron and slag using asubstantial portion of the steelmaking slag as part of the feed materialrequirements for the direct smelting process.

Preferably step (b) includes using at least 70% by weight of thesteelmaking slag as part of the feed material requirements for thedirect smelting process.

More preferably step (b) includes using at least 80% by weight of thesteelmaking slag as part of the feed material requirements for thedirect smelting process.

It is preferred particularly that step (b) includes using at least 90%by weight of the steelmaking slag as part of the feed materialrequirements for the direct smelting process.

Preferably step (b) includes using sufficient steelmaking slag toprovide at least 50% by weight of the flux units of the feed materialrequirements of the direct smelting process.

Preferably the process is an integrated steelmaking process and includesproducing molten iron in at least one ironmaking vessel and supplyingthe molten iron as a ferrous feed material for step (a).

The ironmaking vessel may be any suitable ironmaking vessel such as ablast furnance and a molten bath-based direct smelting vessel.

The process may include using iron produced in step (b) as at least partof the ferrous feed material for producing steel in step (a).

The process may include using iron produced in step (b) and in at leastone other ironmaking vessel as the ferrous feed material for producingsteel in step (a).

Preferably step (b) includes controlling the direct smelting process tosmelt the ferrous feed material and substantially partition phosphorusto the slag.

Preferably the direct smelting process is a HIsmelt process. The directsmelting process may be any other molten bath-based direct smeltingprocess.

Preferably the process includes pre-treating ferrous feed materialincluding steelmaking slag containing iron and flux units for step (b)by at least heating the ferrous feed material in a pre-treatment unit.

Preferably the pre-treatment step includes heating and at leastpartially reducing the ferrous feed material in the pre-treatment unit.

Preferably the pre-treatment step includes preheating the ferrous feedmaterial to at least 400° C., more preferably at least 700° C.

Preferably the pre-treatment step includes preheating the ferrous feedmaterial to a temperature less than 1050° C., more preferably less than900° C.

Preferably the pre-treatment step includes wet scrubbing an offgasproduced in the step and using wet sludge containing steelmaking slag inthe process.

In many situations it may be impractical to rely solely on the use ofsteelmaking slag as the sole source of flux due to the steelmaking slagtypically including only 25 to 35 wt % CaO and the other constituents ofthe slag not being suitable as ironmaking flux. Thus, for a knownaddition of lime, three times the tonnage of steelmaking slag would berequired. In these situations it is appropriate to add one or moreadditional slag forming agents.

Preferably the direct smelting process includes using a slag formingagent to provide flux units for the process in addition to the fluxunits provided by the steelmaking slag.

Preferably the direct smelting process includes injecting the slagforming agent directly into the direct smelting vessel as opposed topretreating the slag forming agent before injection into the vessel asis the case with the steelmaking slag.

Preferably the amount of the slag forming agent injected directly intothe direct smelting vessel is sufficient to provide up to 30% by weightof the flux requirements of the direct smelting process.

Preferably the additional slag forming agent includes calcium oxide.

More preferably the calcium oxide is in the form of lime, burnt lime,dolomite or combinations thereof.

Preferably the process includes cooling the steelmaking slag produced instep (a) prior to using at least a portion of the steelmaking slag instep (b).

Preferably the process further includes reducing the size of the cooledsteelmaking slag prior to adding the steelmaking slag in step (b).

A particularly preferred size range is minus 6 mm.

According to the present invention there is also provided a steelmakingplant for producing molten steel in accordance with the above processthat includes:

(a) a steelmaking apparatus for producing molten steel and moltensteelmaking slag;

(b) an ironmaking apparatus for producing molten iron.

According to the present invention there is also provided a directsmelting process for producing molten iron in a direct smelting vesselcontaining a molten bath of iron and slag, the process including thesteps of:

(a) pre-treating ferrous feed material including steelmaking slagcontaining iron and flux units by at least heating the ferrous feedmaterial in a pre-treatment unit; and

(b) direct smelting molten iron in a direct smelting vessel containing amolten bath of iron and slag using the pre-treated ferrous feed materialincluding steelmaking slag from step (a) as part of the feed materialrequirements for the direct smelting vessel.

Preferably step (a) includes heating and at least partially reducing theferrous feed material.

Preferably step (a) includes preheating the ferrous feed material to atleast 400° C., more preferably at least 700° C.

Preferably step (a) includes preheating the ferrous feed material to atemperature less than 1050° C., more preferably less than 900° C.

Preferably step (a) includes wet scrubbing an offgas produced in thestep and using wet sludge containing steelmaking slag in the process.

Preferably the process includes using a slag forming agent to provideflux units for the process in addition to the flux units provided by thesteelmaking slag.

Preferably the process includes injecting the slag forming agentdirectly into the direct smelting vessel as opposed to pretreating theslag forming agent before injection into the vessel as is the case withthe steelmaking slag.

Preferably the amount of the slag forming agent injected directly intothe direct smelting vessel is sufficient to provide up to 30% by weightof the flux requirements of the direct smelting process.

Preferably the additional slag forming agent includes calcium oxide.

More preferably the calcium oxide is in the form of lime, burnt lime,dolomite or combinations thereof.

Preferably step (b) includes controlling conditions within the directsmelting vessel to smelt the ferrous feed material to iron in the bathand to substantially partition phosphorus to the slag.

Preferably step (b) includes controlling conditions within the directsmelting vessel to partition phosphorus to the slag by maintaining theslag in an oxidising condition whereby the partition ratio of phosphorusin the iron to phosphorus in the slag is at least 1:5.

More preferably the above-described ratio is 1:10.

It is preferred particularly that the ratio be in the range of1:10-1:30.

Preferably step (b) includes controlling conditions within the directsmelting vessel to partition phosphorus to the slag by maintaining theslag temperature to be in the range of 1350-1450° C. and the amount ofFeO in the slag to be at least 3% by weight.

Preferably step (b) includes injecting the pre-treated ferrous feedmaterial and a solid carbonaceous material, and an oxygen-containing gasinto the vessel.

The steelmaking slag added in step (b) may be sourced from anysteelmaking plant using any known steelmaking process including but notlimited to any of the BOF processes and/or electric arc furnaces (EAF).In either case, preferably the steelmaking slag is cooled in accordancewith known techniques so as to be in the form of pellets, granules orpowder.

It is preferred that the steelmaking slag be generated within anintegrated steelmaking plant including at least one direct smeltingvessel and at least one steelmaking vessel at a single site, asdescribed above.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are now described, by way ofexample only, with reference to the accompanying drawings, of which:

FIG. 1 illustrates schematically one embodiment of a process flowsheet;

FIG. 2 illustrates schematically another embodiment of a processflowsheet; and,

FIG. 3 illustrates schematically another (but not the only other)embodiment of a process flowsheet.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

With reference to FIG. 1, there is provided:

(a) an ironmaking apparatus including a pre-treatment unit in the formof a preheater, typically a shaft furnace or a fluidised bed, and

(b) a direct smelting vessel that is suitable particularly for operationby the HIsmelt process as described in International patent applicationPCT/AU96/00197, the contents of which are incorporated herein byreference.

In use, iron ore fines and steelmaking slag obtained from any externalsource are screened to 0 to 6 mm size and are fed to the preheater.Typically, the steelmaking slag includes 35% by weight iron units and25-35% by weight flux units.

The steelmaking slag and the iron ore are heated together in thepreheater to a temperature in the range of 400-900° C. and are fed tothe direct smelting vessel.

The direct smelting vessel includes injection lances (not shown) thatreceive hot ore fines and hot steelmaking slag from the preheater andinject these hot solids at a temperature of the order of 350-850° C.into the vessel.

Preheating steelmaking slag is not subject to the difficultiesassociated with preheating flux such as lime. The main difficulty withpreheating lime is that lime that is taken up with offgas from thepreheater tends to dissolve in wash water in wet scrubbers (not shown)that clean the offgas and are lost from the process. This is a seriousissue because of the high cost of flux. Steelmaking slag does notdissolve in scrubber water and therefore can be recovered in wet sludgeproduced in wet scrubbers and re-used in the process.

In use, carbonaceous material, typically coal, and additionalslag-forming fluxes, typically lime are also fed to the vessel.

The direct smelting vessel includes injection lances (not shown) thatreceive and inject the carbonaceous material and the additionalslag-forming fluxes into the vessel. The carbonaceous material andfluxes may be blended together and injected and/or injected separately.

The injection of these additional fluxes directly into the vessel, asopposed to passing the additional fluxes through the preheater first asis the case with the steelmaking slag, is important as a controlmechanism of the process. Typically, such direct flux injection is up to30% by weight of the total flux requirements.

The HIsmelt process also operates with air or oxygen-enriched air andtherefore generates substantial volumes of offgas which may be used forpreheating the materials fed to the direct smelting vessel.

The process conditions within the direct smelting vessel are controlledsuch that the phosphorus in any of the solid materials fed to the vesselpartitions preferentially to the slag. In the case of the HIsmeltprocess, this is achieved by ensuring that the FeO in slag is in therange 4-6% by weight and the temperature is in the range of 1400-1450°C. Under these process conditions, the partition ratio of phosphorus inthe slag to phosphorus in metal is in the range of 5:1 to 20:1.

The hot metal produced in the direct smelting vessel is sufficiently lowin phosphorus (less than 0.05% by weight) to be readily used as a feedmaterial to a downstream steelmaking plant (not shown) which may belocated on the same or at another site.

With reference to FIG. 2, there is provided an integrated steelmakingplant including one or more than one BOF and a direct smelting apparatusfor producing hot metal as a feed to the one or more than one BOF. Thesteelmaking slag from the BOF is recycled to form one component of theslag-forming flux to the direct smelting apparatus. The direct smeltingapparatus includes a preheater unit and a direct smelting vesseloperating in accordance with the HIsmelt process as shown in anddescribed above with reference to FIG. 1.

The one or more than one BOF is typically also charged with scrap metalprior to the addition of the ladles of hot metal from the directsmelting vessel. Typically, the scrap is charged first before the hotmetal to avoid splashing. After the scrap is charged, the hot metal ischarged into the BOF. Based on the chemistry of the charge and thetemperature and the specific alloy being produced in the steelmakingprocess, the amounts of flux and oxygen added to the BOF are calculated.As for ironmaking, the typical flux added includes CaO (from burnt lime)and MgO (from dolomitic lime).

When the oxygen blow is finished, the steelmaking slag is allowed tofloat to the top of the bath of the molten steel. The steel is tappedfrom the BOF followed by tapping of the steelmaking slag.

The steelmaking slag is typically tapped into slag pots (not shown) andeither quenched or allowed to cool. The cooled slag is fed to a meansfor processing the steelmaking slag, which may include size reductionapparatus such as crushers and screens and/or magnetic separators forrecovering carried over steel. The cooled and screened steelmaking slagis then fed to the preheater of the ironmaking apparatus.

In the arrangement of FIG. 3, in use, the steelmaking apparatus, such asa BOF, is charged with (a) hot metal from a direct smelting vessel asdescribed above with reference to FIG. 2 and (b) hot metal from atraditional blast furnace. The steelmaking slag generated in thesteelmaking apparatus is recycled to the direct smelting apparatus inthe manner described above with reference to FIG. 2. As the traditionalblast furnace is not able to tolerate high phosphorus feeds, thesteelmaking slag is not recycled as a flux to the blast furnace. Thetypical partition ratio of phosphorus in the slag to phosphorus in theiron for a blast furnace is 0.1 compared with 10 to 20 for the HIsmeltprocess.

The applicant has carried out computer modelling on the processflowsheets shown in FIGS. 2 and 3 and a Comparative flowsheet.

The modelling work was based on the use of a pre-treatment unit/directsmelting vessel operating in accordance with the HIsmelt process andproducing of the order of 0.8 million tonnes per annum (Mt/a) of molteniron.

The modelling work was also based on the use of a BOF steelmaking vesselproducing 0.7 Mt/a in the case of the Comparative and FIG. 2 flowsheetsand 2.4 Mt/a in the case of the FIG. 3 flowsheet.

Brief details of the results of the modelling work for the Comparativeflowsheet and the FIGS. 2 and 3 flowsheets are set out below.

Comparative Flowsheet—pre-treatment unit/direct smelting vessel andsteelmaking vessel, with no steelmaking slag return to the pre-treatmentunit.

In accordance with the model, the hot metal feed to the steelmakingvessel is 104.9 t/hr iron. The steelmaking vessel produces 6.6 t/hr slagand 1.6 t/hr dust. The direct smelting vessel takes no slag and no dust.The slag and dust are disposed of in accordance with standard practices.The iron ore feed to the direct smelting vessel is 197.5 t/hr iron orefines and recycled smelting process dust. The direct smelting vesselproduces 32.9 t/hr slag and 104.9 t/hr iron.

FIG. 2 Flowsheet—pre-treatment unit/direct smelting vessel andsteelmaking vessel, with steelmaking slag return to the pre-treatmentunit.

In accordance with the model, the hot metal feed to the steelmakingvessel comprises 105.7 t/hr iron. The steelmaking vessel produces 6.7t/hr slag and 1.6 t/hr dust. The direct smelting vessel takes 6.0 t/hrslag and 1.4 t/hr dust. These amounts equate to 89.5% and 87.5%,respectively of the slag and dust produced by the steelmaking vessel.The total iron ore feed to the direct smelting vessel is 192.8 t/hr ironore fines, steelmaking slag, steelmaking dust, and recycled smeltingprocess dust. The direct smelting vessel produces 33.9 t/hr slag and105.7 t/hr iron.

When compared with the Comparative flowsheet, and bearing in mind thatboth processes produced substantially the same amounts of molten ironand the same amounts of molten steel, it is evident that the impact ofslag return was to:

(a) reduce total slag produced by the steelmaking vessel and the directsmelting vessel by 4.9 t/hr; and (b) reduce total iron ore feedrequirements for the direct smelting vessel by 4.7 t/hr.

FIG. 3 Flowsheet—pre-treatment unit/direct smelting vessel, blastfurnace, and steelmaking vessel, with steelmaking slag return to thepre-treatment unit.

In accordance with the model, the hot metal feed to the steelmakingvessel comprises 200 t/hr iron from the blast furnace and 107.9 t/hrfrom the direct smelting vessel. The steelmaking vessel produces 32.6t/hr slag and 5.6 t/hr dust. The direct smelting vessel takes 27.7 t/hrslag and 4.7 t/hr dust. These amounts equate to 84.9% and 83.9%,respectively of the slag and dust produced by the steelmaking vessel.The total iron ore feed to the direct smelting vessel is 205.6 t/hr ironore fines, steelmaking slag, steelmaking dust, and recycled smeltingprocess dust. The direct smelting vessel produces 38.1 t/hr slag and107.9 t/hr iron.

It is evident from the above that a significant amount (27.7 t/hr) ofslag from the steelmaking vessel is used in the direct smelting vesseland thereby reduces the iron and flux units required from other sources.

The present invention has a number of advantages over the prior art,including:

(a) reducing the amount of waste steelmaking slag required to bedisposed of from a steelmaking plant;

(b) recovering flux units and iron units in the steelmaking slag; and,

(c) reducing the quantity of fresh flux and iron units required to befed to an ironmaking process when using recycled steelmaking slag.

Many modifications may be made to the embodiments of the presentinvention described above without departing from the spirit and scope ofthe invention.

For example, whilst the embodiments of the present invention have beendescribed in the context of the use of the HIsmelt process, it isunderstood that the present invention is applicable to any ironmakingprocess whereby the phosphorus fed to the ironmaking process reportspreferentially to the ironmaking slag. Such other ironmaking processesmay include by way of example the Romelt and DIOS processes.

In addition, whilst the embodiments of the present invention includepre-treatment units in the form of preheaters, the present inventionextends to any suitable form of pre-treatment units and to arrangementsthat do not include preheaters.

1-37. (canceled)
 38. A process that includes the steps of: (a) producingmolten steel and molten steelmaking slag in a steelmaking vessel, thesteelmaking slag including iron units and flux units; and (b) producingmolten iron in a direct smelting process in a direct smelting vesselcontaining a molten bath of iron and iron-making slag by supplying ironore or pre-treated iron ore and carbonaceous material to the directsmelting vessel as a part of the feed material requirements of thedirect smelting process, by injecting an oxygen-containing gas into thevessel to combust reaction gases released from the bath and by using asubstantial portion of the steelmaking slag from step (a) as part of theflux unit requirements for the direct smelting process and therebysmelting the iron ore or pre-treated iron ore and iron units to producemolten iron, wherein the direct smelting process includes controllingconditions within the direct smelting vessel to substantially partitionphosphorous to the iron-making slag.
 39. The process defined in claim38, wherein controlling conditions within the direct smelting vesselinvolves maintaining the iron-making slag in an oxidising condition bycontrolling the amount of FeO in the iron-making slag to be at least 3%by weight.
 40. The process defined in claim 38, wherein step (b)includes using at least 70% by weight of the steelmaking slag as part ofthe feed material requirements for the direct smelting process.
 41. Theprocess defined in claim 38, wherein step (b) includes using at least80% by weight of the steelmaking slag as part of the feed materialrequirements for the direct smelting process.
 42. The process defined inclaim 38, wherein step (b) includes using at least 90% by weight of thesteelmaking slag as part of the feed material requirements for thedirect smelting process.
 43. The process defined in claim 38, whereinstep (b) includes using sufficient steelmaking slag to provide at least50% by weight of the flux units of the feed material requirements of thedirect smelting process.
 44. The process defined in claim 38, whereinthe process is an integrated steelmaking process and includes producingmolten iron in at least one ironmaking vessel and supplying the molteniron as a ferrous feed material for step (a).
 45. The process defined inclaim 38, further including using iron produced in step (b) as at leastpart of the ferrous feed material for producing steel in step (a). 46.The process defined in claim 38, further including using iron producedin step (b) and in at least one other ironmaking vessel as the ferrousfeed material for producing steel in step (a).
 47. The process definedin claim 38, wherein the direct smelting process is a molten bath-basedprocess in which solid feed materials are injected deep into the moltenbath.
 48. The process defined in claim 38, further includingpre-treating ferrous feed material including the steelmaking slagcontaining iron and flux units for step (b) by at least heating theferrous feed material in a pre-treatment unit.
 49. The process definedin claim 48, wherein the pre-treatment step includes preheating theferrous feed material to at least 400° C.
 50. The process defined inclaim 49, wherein the pre-treatment step includes preheating the ferrousfeed material to at least 700° C.
 51. The process defined in claim 48,wherein the pre-treatment step includes preheating the ferrous feedmaterial to a temperature less than 1050° C.
 52. The process defined inclaim 48, wherein the pre-treatment step includes preheating the ferrousfeed material to a temperature less than 900° C.
 53. The process definedin claim 48, wherein the pre-treatment step includes wet scrubbing anoffgas produced in the step and using wet sludge containing steelmakingslag in the process.
 54. The process defined in claim 48, wherein thedirect smelting process includes using a slag forming agent to provideflux units for the process in addition to the flux units provided by thesteelmaking slag.
 55. The process defined in claim 54, wherein thedirect smelting process includes injecting the slag forming agentdirectly into the direct smelting vessel as opposed to pretreating theslag forming agent before injection into the vessel as is the case withthe steelmaking slag.
 56. The process defined in claim 38, wherein anamount of slag forming agent injected directly into the direct smeltingvessel is sufficient to provide up to 30% by weight of the fluxrequirements.
 57. The process defined in claim 56, wherein the slagforming agent includes calcium oxide.
 58. The process defined in claim38, further including cooling the steelmaking slag produced in step (a)prior to using at least a portion of the steelmaking slag in step (b).59. The process defined in claim 58, further including reducing the sizeof the cooled steelmaking slag prior to adding the steelmaking slag instep (b).
 60. A direct smelting process for producing molten iron in adirect smelting vessel containing a molten bath of iron and iron-makingslag, the process including the steps of: (a) pre-treating ferrous feedmaterial including steelmaking slag containing iron units and flux unitsin a pre-treatment unit by at least heating and at least partiallyreducing the ferrous feed material; and (b) direct smelting molten ironin a direct smelting vessel containing a molten bath of iron andiron-making slag by supplying iron ore or pre-treated iron ore andcarbonaceous material to the direct smelting vessel as a part of thefeed material requirements of the direct smelting process, by injectingan oxygen-containing gas into the vessel to combust reaction gasesreleased from the bath and by using a substantial portion of thepre-treated ferrous feed material including steelmaking slag from step(a) as part of the feed material requirements for the direct smeltingprocess and thereby smelting the iron ore or pre-treated iron ore andiron units to produce molten iron and wherein the direct smelting molteniron involves controlling conditions within the direct smelting vesselto substantially partition phosphorous to the iron-making slag.
 61. Theprocess defined in claim 60, wherein controlling conditions in thedirect smelting vessel involves maintaining iron-making slag in anoxidising condition by controlling the amount of FeO in the iron-makingslag to be at least 3% by weight.
 62. The process defined in claim 60,wherein step (a) includes heating and at least partially reducing theferrous feed material.
 63. The process defined in claim 60, wherein step(a) includes heating the ferrous feed material to at least 400° C. 64.The process defined in claim 60, wherein step (a) includes heating theferrous feed material to at least 700° C.
 65. The process defined inclaim 60, wherein step (a) includes preheating the ferrous feed materialto a temperature less than 1050° C.
 66. The process defined in claim 60,wherein step (a) includes preheating the ferrous feed material to atemperature less than 900° C.
 67. The process defined in claim 60,wherein step (a) includes wet scrubbing an offgas produced in the stepand using wet sludge containing steelmaking slag in the process.
 68. Theprocess defined in claim 60, wherein step (b) includes using a slagforming agent to provide flux units for the process in addition to theflux units provided by the steelmaking slag.
 69. The process defined inclaim 68, wherein step (b) includes injecting the slag forming agentdirectly into the direct smelting vessel as opposed to pretreating theslag forming agent before injection in to the vessel as is the case withthe steelmaking slag.
 70. The process defined in claim 60, wherein anamount of slag forming agent injected directly into the direct smeltingvessel is sufficient to provide up to 30% by weight of the fluxrequirements.
 71. The process defined in claim 60, wherein an additionalslag forming agent includes calcium oxide.
 72. The process defined inclaim 60, wherein step (b) includes controlling conditions within thedirect smelting vessel to partition phosphorus to the slag bymaintaining the slag in an oxidising condition whereby the partitionratio of phosphorus in the iron to phosphorus in the slag is at least1:5.
 73. The process defined in claim 60, wherein step (b) includescontrolling conditions within the direct smelting vessel to partitionphosphorus to the slag by maintaining the slag in an oxidising conditionwhereby the partition ratio of phosphorus in the iron to phosphorus inthe slag is at least 1:10.
 74. The process defined in claim 60, whereinstep (b) includes controlling conditions within the direct smeltingvessel to partition phosphorus to the slag by maintaining the slag in anoxidising condition whereby the partition ratio of phosphorus in theiron to phosphorus in the slag is in the range of 1:10 to 1:30.
 75. Theprocess defined in claim 60, wherein step (b) includes controllingconditions within the direct smelting vessel maintaining the slagtemperature to be in the range of 1350-1450° C.